78. The aggregate of the amounts contemplated in section 77 that is to be computed under this section is the aggregate of:(a) all amounts received by the taxpayer before 1972 and after the commencement of the partnership’s first fiscal period ending after 1971 according to his share of the partnership profits or partnership capital; and
(b) all amounts attributable to the disposition by the taxpayer after 1971 and before the time contemplated in section 77 of a part of his interest in the partnership, equal to such portion of the adjusted cost base to him of the interest immediately before the disposition as may reasonably be regarded as attributable to the part of the interest so disposed of.